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Optical Multistage Interconnection Networks: New Challenges and Approaches
 IEEE Communications Magazine
, 1999
"... Optical interconnections for communication networks and multiprocessor systems have been studied extensively. A basic element of optical switching networks is a directional coupler with two inputs and two outputs (hereafter referred to simply as switching elements or SEs). Depending on the control v ..."
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Optical interconnections for communication networks and multiprocessor systems have been studied extensively. A basic element of optical switching networks is a directional coupler with two inputs and two outputs (hereafter referred to simply as switching elements or SEs). Depending on the control voltage applied to it, an input optical signal is coupled to either of the two outputs, setting the SE to either the straight or the cross state. A class of topologies that can be used to construct optical networks is multistage interconnection networks (MINs), which interconnect their inputs and outputs via several stages of SEs. Although optical MINs hold great promises and have demonstrated advantages over their electronic counterparts, they also introduce new challenges such as how to deal with the unique problem of avoiding crosstalk in the SEs. In this paper, we survey the research carried out, including major challenges encountered and approaches taken, during the past few years on opt...
Permutation capability of optical multistage interconnection network
 JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING” , PP.60,
, 2000
"... In this paper, we study optical multistage interconnection networks (MINs). Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of highperformance computing/commu ..."
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In this paper, we study optical multistage interconnection networks (MINs). Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of highperformance computing/communication applications. Although optical MINs hold great promise and have demonstrated advantages over their electronic counterpart, they also hold their own challenges. Due to the unique properties of optics, crosstalk in optical switches should be avoided to make them work properly. Most of the research work described in the literature are for electronic MINs, and hence, crosstalk is not considered. In this paper, we introduce a new concept, semipermutation, to analyze the permutation capability of optical MINs under the constraint of avoiding crosstalk, and apply it to two examples of optical MINs, banyan network and Benes network. For the blocking banyan network, we show that not all semipermutationsare realizable in one pass, and give the number of realizable semipermutations. For the rearrangeable Benes network, we show that any semipermutation is realizable in one pass and any permutation is realizable in two passes under the constraint of avoiding crosstalk. A routing algorithmfor realizing a semipermutationin a Benes network is also presented. Withthe speed and bandwidthprovided by current optical technology, an optical MIN clearly demonstrates a superior overall performance over its electronic MIN counterpart.
Equivalent Permutation Capabilities Between TimeDivision Optical Omega Networks and NonOptical ExtraStage Omega Networks
 IEEE/ACM Transactions on Networking
, 2001
"... Because signals carried by two waveguides entering a common switch element would generate crosstalk, a regular multistage interconnection network (MIN) cannot be directly used as an optical switch between inputs and outputs in an optical network. A simple solution is to use a 2 2 cubetype MIN to p ..."
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Cited by 17 (4 self)
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Because signals carried by two waveguides entering a common switch element would generate crosstalk, a regular multistage interconnection network (MIN) cannot be directly used as an optical switch between inputs and outputs in an optical network. A simple solution is to use a 2 2 cubetype MIN to provide the connections, which needs a much larger hardware cost. A recent research proposed another solution, called the timedomain approach, that divides the optical inputs into several groups such that crosstalkfree connections can be provided by an regular MIN in several time slots, one for each group. Researchers studied this approach on Omega networks and defined the class set to be the set ofpermutations realizable in two time slots on an Omega network. They proved that the size of is larger than the size of class\Omega , where\Omega consists of allpermutations admissible to a regular (nonoptical) Omega network. This paper first presents an optimal ( log ) time algorithm for identifying whether a given permutation belongs to class or not. Using this algorithm, this paper then proves an interesting result that the class is identical to the class\Omega 1which represents the set of permutations admissible to a nonoptical oneextra stage Omega network. Index TermsConflict graph, crosstalkfree connection, dilated MIN, Omega network, optical switch, timedomain approach. I.
Analyzing the performance of optical multistage interconnection networks with limited crosstalk
, 2007
"... Analytical modeling techniques can be used to study the performance of optical multistage interconnection network (OMIN) effectively. MINs have assumed importance in recent times, because of their costeffectiveness. An N × N MIN consists of a mapping from N processors to N memories, with log 2 N ..."
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Cited by 5 (0 self)
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Analytical modeling techniques can be used to study the performance of optical multistage interconnection network (OMIN) effectively. MINs have assumed importance in recent times, because of their costeffectiveness. An N × N MIN consists of a mapping from N processors to N memories, with log 2 N stages of 2 × 2 switches with N/2 switches per stage. The interest is on the study of the performance of unbuffered optical multistage interconnection network using the banyan network. The uniform reference model approach is assumed for the purpose of analysis. In this paper the analytical modeling approach is applied to an N × N OMIN with limited crosstalk (conflicts between messages) up to (log 2 N − 1). Messages with switch conflicts satisfying the constraint of (log 2 N − 1) are allowed to pass in the same group, but in case of a link conflict, the message is routed in a different group. The analysis is performed by calculating the bandwidth and throughput of the network operating under a load l and allowing random traffic and using a greedy routing strategy. A number of equations are derived using the theory of probability and the performance curves are plotted. The results obtained show that the
Message Routing and Scheduling in Optical Multistage Networks Using Simulated Annealing
"... Optical Multistage Interconnection Networks (MINs) suffer from opticalloss during switching and crosstalk problem in the switches. The crosstalk problem is solved by routing messages using time division multiplexing (TDM) approach. This paper focuses on minimizing the number of groups (time slots) ..."
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Optical Multistage Interconnection Networks (MINs) suffer from opticalloss during switching and crosstalk problem in the switches. The crosstalk problem is solved by routing messages using time division multiplexing (TDM) approach. This paper focuses on minimizing the number of groups (time slots) required to realize a permutation. Many researchers concentrated on this NPhard problem and concluded that AI algorithms perform better than the heuristic algorithms. They also showed that majority of the times the performance of Genetic Algorithm (GA) was better than Simulated Annealing Algorithm (SAA). In this research, we implement a new approach to minimize the number of passes required for scheduling a given permutation. A combinational method is developed which comprises the use of Bayesian inference method on GA and SAA to always guarantee the best solution, instead of only using either GA or SAA. Simulations are performed in java using multiple threads to run SA and GAA in parallel and to evaluate the performance of the new method. The results are then compared to those obtained from GA and SAA. 1.
Optimal AlltoAll Personalized Exchange in a Class of Optical Multistage Networks
, 2000
"... Alltoall personalized exchange is one of the most dense collective communication patterns and occurs in many important parallel computing/networking applications. In this paper, we look into the issue of realizing alltoall personalized exchange in optical multistage networks. Advances in electro ..."
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Cited by 4 (1 self)
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Alltoall personalized exchange is one of the most dense collective communication patterns and occurs in many important parallel computing/networking applications. In this paper, we look into the issue of realizing alltoall personalized exchange in optical multistage networks. Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of highperformance computing/communication applications. Although optical multistage networks hold great promise and have demonstrated advantages over their electronic counterpart, they also hold their own challenges. Due to the unique properties of optics, crosstalk in optical switches should be avoided to make them work properly. In this paper, we will provide an optimal scheme for realizing alltoall personalized exchange in a class of uniquepath, selfrouting optical multistage networks crosstalkfree. The basic idea of realizing alltoall personalized exchange in such a multistage network is to transform it to multiple semipermutations, each of which can be realized crosstalkfree in a single pass, and take advantage of pipelined message transmission in consecutive passes. As can be seen, the time complexity of our alltoall personalized exchange algorithms matches the lower bound of the communication delay in this type of network.
A TwoLevel Process for Diagnosing Crosstalk in Photonic Dilated Benes Networks
 JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING
, 1997
"... A twolevel process for diagnosing crosstalk in photonic Dilated Benes Networks (DBNs) is presented. At level one is the TestAllSwitches (TAS) procedure, which obtains the crosstalk ratios of each and every switch in a N x N DBN in 4N tests using O(N \Delta log² N) calculations. One of its applica ..."
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A twolevel process for diagnosing crosstalk in photonic Dilated Benes Networks (DBNs) is presented. At level one is the TestAllSwitches (TAS) procedure, which obtains the crosstalk ratios of each and every switch in a N x N DBN in 4N tests using O(N \Delta log² N) calculations. One of its applications is to identify single or multiple crosstalkfaulty switches in the DBN which generate excessive crosstalk. To reduce the number of tests and amount of computation when diagnosing only a few switches suspected of crosstalkfaulty along an arbitrary path, the TestOnePath (TOP) procedure at level two is proposed. A recursive algorithm applicable to both procedures is used to configure the DBN for each test such that the necessary power measurements of the signals can be taken accurately. An important feature of the proposed diagnostic process is its suitability for automated test generation.
Parallel Routing and Wavelength Assignment for Optical Multistage Interconnection Networks
 in: Proceedings of the International Conference on Parallel Processing (ICPP’04
, 2004
"... Multistage interconnection networks (MINs) are among the most efficient switching architectures in terms of the number of switching elements (SEs) used. For optical MINs (OMINs), two I/O connections with neighboring wavelengths cannot share a common SE due to crosstalk. In this paper, we focus on ..."
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Multistage interconnection networks (MINs) are among the most efficient switching architectures in terms of the number of switching elements (SEs) used. For optical MINs (OMINs), two I/O connections with neighboring wavelengths cannot share a common SE due to crosstalk. In this paper, we focus on the wavelength dilation approach, in which the I/O connections sharing a common SE will be assigned different wavelengths with enough wavelength spacing. We first study the permutation capacity of OMINs, then propose fast parallel routing and wavelength assignment algorithms for OMINs. By applying our permutation decomposition and graph coloring techniques, the proposed algorithms can route any permutation without crosstalk in wavelengthrearrangeable spacestrictsense Banyan networks and wavelengthrearrangeable spacerearrangeable Benes networks in polylogarithmic time using a linear number of processors. 1.
An efficient approach for message routing in optical omega network
 International Journal of The Computer, the Internet and Management
, 2006
"... Optimal routing in Optical Omega Network (OON) is an NPhard problem. A major problem called crosstalk is introduced by OON, which is caused by coupling two signals within a Switching Element (SE). Many heuristic algorithms were designed by many researchers to perform this routing such as sequential ..."
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Optimal routing in Optical Omega Network (OON) is an NPhard problem. A major problem called crosstalk is introduced by OON, which is caused by coupling two signals within a Switching Element (SE). Many heuristic algorithms were designed by many researchers to perform this routing such as sequential algorithm, degreedescending algorithm. Routing the messages in degreedecreasing of the message conflicts gave best performance among them. The Simulated Annealing (SA) algorithm also was used to improve the performance of solving the problem and gave best result. This paper presents an efficient approach for message routing in OON. The proposed approach that combines of SA algorithm with the best heuristic algorithms gave much better result in a very minimal time.